Scratchbuilding Fully-Articulated Hands

This tutorial is part of my Ice Queen Palace Athene build.

What you'll need:

3mm Tamiya plastic beams
0.5mm Tamiya plapates
IC socket pins (sewing pins will do, socket pins are more ideal)

Microsaw/Etching saw
Pin Vise (with 0.5mm bit)
Modeling Knife (with a slightly blunt blade)

And a lot of patience...

Part One

I've actually done a smaller version using both 2mm beams (left) and two 1mm beams sandwiched between 0.5mm plates. I abandoned the idea when I realized that the hands will be too small for my taste, aside from being too flimsy in the long run.

 

I've redone everything from the beginning, mainly because I have issues with the prototype. This version will have laterally flexible phalanges (similar to an actual hand where the digits are able to separate from the knuckles) and not restrictive like in the prototype.

For this, I've marked the 3mm beam's cross section with a pencil where I would cut.

Now, it's only a matter of repeating the previous steps a few times to make the other sections. To do the other end, the reverse is done, where material is removed from opposite sides instead of the middle.

Of course, it's relatively easier to do this on longer beams, and more difficult when you're doing the other end AFTER cutting, then used my knife to score the beam along the pencil lines.

Next, I used a Hasegawa etching saw (0.15, I think), and cut material away. I always cut less material so I can gauge the tightness of the joint later on, removing material as needed. If I happen to cut too much, I employ the superglue approach.

 

You can also use the saw's grip marks as depth guides, though, I usually deepen the cut so I can adjust later one when I reshape the ends,

 

then used a 0.5 drill to bore a hole along the base of the material I need removed,

 

and 
Voila!

 

There you have it. The fingertips is just as simple as carving material away and refining the shape with a file and sandpaper.

Part Two

The Drilling Menace...

Though it's relatively easy to drill holes, it becomes quite a challenge when aligning holes on the joints. Instead of drilling the holes in one go, I separated the joints parts. Using a 0.5mm bit, I drilled holes on the outer part of the joint which sandwiches the "tongue,"

making sure that the holes are aligned as much as possible. (I did this just by estimating the hole position, it can be done better by pre-marking the hole position with a pin).

Once that's done, reinsert the tongue and align it as close to the joint. You can use the pre-drilled holes as a guide for drilling the tongue.

Now, the tongue itself is a little more complicated to do, since I had to shape it a little bit into a rounded edge, to facilitate the movement of the articulation.

 

I used male/male IC pins (brass) for the joints. One end is slightly thinner and longer than the other, and I used the slightly thinner part to temporarily hold the joint while I make adjustments to the joint. I used the slightly thicker part to pin the joint itself (I tend to lose a lot of these things after I cut them during handling, even with tweezers, but I find that holding them with my fingers and inserting them into the holes is easier).

 

And, there you go.

As an addition, some dry sanding images. The left shows a hand part sanded with 280 grit paper, the right, sanded with 280, then finished with 600 grit. Depending on how much smoother you want it, you can try wet sanding with higher grit paper.

 

 
Part Three

I modified the Queen's stock manipulator further to fit the articulated thumb, like I've done with the prototype. 

 

I drilled a small diameter (0.5mm) but deep hole (I used the drill itself as a depth guide, setting it at just enough length on the pin vise, and made it deep enough for trimming later on) on the cross section center of the second phalange, this will serve as the pivot for the thumb.

Second, I enlarged the hole with a 1.2mm bit at the same depth as the original.

Third, I enlarged the hole with a 2.0mm drill bit. This progressive enlargement prevents stress-induced damage and actually allows a more precise drilling along the length of the beam.

 

Next, I made a plug from a separate piece of beam by marking the beam with a knife, and started carving from there, trimming material away until I have a plug that fits snugly (with considerable ease of rotation) to the hole I made earlier.

 

 

Test fit.

 

 
The sections assembled temporarily, with some of the pins still uncut.

 

Another "small" update:

Puttyless seamline removal (which will be another tutorial). I found that pre-sanding seamlines (parts should be snapfitted) BEFORE cementing them actually makes for easier removal. In some cases, even just pre-sanding (280/400/600 grit) can make seamlines disappear. You wouldn't even know the difference between which forearm was a snapfit, and which was already cemented and sanded smooth.


 

This method actually eliminates the need for too much "ooze" resulting from the melting of the adjoining plastic and the resin of the cement.  In my experience, that ooze actually damages the nearby surface, prompting me to sand more in order to achieve a smooth surface.

I also reshaped the hand guard protrusions.

 

And I just can't NOT have any Red...

 

The forearms, assembled with the manipulators (I shot these with the prototype).

I think it was the right decision to "ditch" the prototype. The Queen's hands now look more menacing with the lateral movements. I'm still deciding whether to paint the phalanges or not, since they look fine as they are (needing only some more sanding) without paint.